The present invention relates to a wiring method for a semiconductor integrated circuit with reduced noise and a computer product.
FIG. 21 is a layout diagram of an example of a conventional semiconductor integrated circuit. This semiconductor integrated circuit includes elements 81, 82 and 83, a signal line 84 connecting the elements 81 and 83 with each other, and a signal line 85 connecting the elements 82 and 83 with each other. A predetermined standard for time operation guarantee and the like is prescribed for a time gap between a rise time or fall time of a signal that flows through the signal line 84 and a rise time or fall time of a signal that flows through the signal line 85. The signal lines 84 and 85 are kept as short as possible in order to easily achieve this standard.
FIG. 22 is a timing chart showing one example of signals that flow through the conventional signal lines 84 and 85. It is assumed, for example, that there is a prescribed standard of a51 sec as a gap between a timing that a signal A51 that flows through the signal line 84 rises from a low level to a high level and a timing that a signal B51 that flows through the signal line 85 rises from a low level to a high level. Since the signal lines 84 and 85 are wired as short as possible, the signals A51 and B51 rise steeply. Therefore, a time gap b51 sec between the rise time of the signal line A51 and the rise time of the signal line B51 becomes sufficiently small in comparison to the standard time gap a51 sec.
FIG. 23 is a timing chart showing another example of signals that flow through the conventional signal lines 84 and 85. It is assumed, for example, that there is a prescribed standard of a52 sec as a gap between a timing that a signal A52 that flows through the signal line 84 falls from a high level to a low level and a timing that a signal B52 that flows through the signal line 85 falls from a high level to a low level. Since the signal lines 84 and 85 are wired as short as possible, the signals A52 and B52 fall steeply. Therefore, a time gap b52 sec between the fall time of the signal line A52 and the fall time of the signal line B52 becomes sufficiently small as compared to the standard time gap of a52 sec.
FIG. 24 is a timing chart showing still another example of signals that flow through the conventional signal lines 84 and 85. It is assumed, for example, that there is a prescribed standard of a53 sec as a gap between a timing that a signal A53 that flows through the signal line 84 rises from a low level to a high level and a timing that a signal B53 that flows through the signal line 85 falls from a high level to a low level. Since the signal lines 84 and 85 are wired as short as possible, the signals A53 and B53 fall steeply. Therefore, a time gap b53 sec between the rise time of the signal line A53 and the fall time of the signal line B53 becomes sufficiently small as compared to the standard time gap of a53 sec.
According to the above prior-art techniques, the signal lines are wired as short as possible. As a consequence, the signals rise and fall steeply. When the signals rise and fall steeply like this, there is a drawback that overshoot or undershoot is generated which results into an increase in the noise.
It is an object of the present invention to provide a wiring method for a semiconductor integrated circuit with reduced noise by suppressing occurrences of overshoot and undershoot, and a computer-readable recording medium storing a program for making the computer execute this method.
In the wiring method for a semiconductor integrated circuit according to one aspect of the present invention, signal lines are wired to maximize a gap in timing between the signal lines within a predetermined standard, thereby slowing a rise and a fall of signals.
In the wiring method for a semiconductor integrated circuit according to another aspect of the present invention, the lengths of signal lines are extended to maximize a gap in timing between the signal lines within a predetermined standard, thereby slowing a rise and a fall of signals.
In the wiring method for a semiconductor integrated circuit according to still another aspect of the present invention, the widths of signal lines are expanded to maximize a gap in timing between the signal lines within a predetermined standard, thereby slowing a rise and a fall of signals.
In the wiring method for a semiconductor integrated circuit according to still another aspect of the present invention, one or a plurality of through-holes are provided on signal lines to maximize a gap in timing between the signal lines within a predetermined standard, thereby slowing a rise and a fall of signals.
In the wiring method for a semiconductor integrated circuit according to still another aspect of the present invention, signal lines are branched to maximize a gap in timing between the signal lines within a predetermined standard, thereby slowing a rise and a fall of signals.
In the wiring method for a semiconductor integrated circuit according to still another aspect of the present invention, signal lines are provided with one or a plurality of parallel routes to maximize a gap in timing between the signal lines within a predetermined standard, thereby slowing a rise and a fall of signals.
A computer-readable recording medium according to still another aspect of the present invention is recorded with a program for making the computer execute any one of the above methods relating to the invention. With this arrangement, it is possible to make the computer execute the methods of the above-described methods relating to the invention.
In this case, the xe2x80x9ccomputer-readable recording mediumxe2x80x9d includes a xe2x80x9cportable physical mediumxe2x80x9d such as a magnetic disk like a floppy disk, a semiconductor memory (including that incorporated in a cartridge or a PC card) like a ROM, an EPROM, an EEPROM, a flash ROM, etc., an optical disk like a CD-ROM, a DVD, etc., an optical magnetic disk like an MO, etc., and a xe2x80x9cfixed physical mediumxe2x80x9d like a ROM, a RAM, a hard disk, etc. that are incorporated in various types of computer systems.
Further, the xe2x80x9ccomputer-readable recording mediumxe2x80x9d may also include a communication medium for short-time holding a program like a communication line for transmitting a program via a network like a LAN, a WAN, Internet, etc. The xe2x80x9cprogramxe2x80x9d is a one that describes a data processing method. A language to be described and a describing method are not particularly limited, and formats of a source code, a binary code and an execution format are not limited. Further, the xe2x80x9cprogramxe2x80x9d is not necessarily limited to a one formed in a single structure, but also includes a distributed structure as a plurality of modules and libraries, and a program that achieves its function in co-operation with separate programs of an OS and the like.
Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings.